Rock drill and like cutting machine



A. BERNER. ROCK DRILL AND LIKE CUTTING MACHINE.

APPLICATION FILED JAN. 8. 1914- Patented May 23,1922

rrn

AUGUST BEE/NEE, OF NUREMBERG, GERMANY, ASS IGNOB T0 C. 8: E. FEIN,ELEGKTRO- TECHNISCHE FILBRIK, OF STUTTGART, GERMANY.

ROCK DRILL AN D LIKE CUTTING MACHINE.

' Specification of Letters Patent.

Patented May 231, 1922.

Application filed January 8, 1914. Serial No. 810,949.

(GRANTED UNDER THE TROVISIONS OF THE ACT OF MARCH 3, 1921, 41 STAT. L,1313.)

To all whom it may concern:

Be it known that 1, AUGUST BERNER, a subject of the German Emperor,residing at Nuremberg, in the Empire of Germany, have invented certainnew and useful Improvements in and Relating to Rock Drills and likeCutting Machines, of which the following is a specification.

This invention relates to improvements in rock drilling and othercutting machines in which the movement of the hammer piston is operatedby the pressure and suction action of a single-acting air pump.

In the ordinary pneumatic tools of this kind the commencement of thesuction of the air takes place each time at a given position of the pumppiston.

This method of governing the air pressure does not suiiiciently meet theactual working conditions, as the movement of the pump and hammerpistons never entirely act in the same or opposite directions. Thecommencement of the suction of the air should howeveralways bedetermined by the position of thehammer piston.

According to this invention the commence ment of the suction of the airis initiated by the hammer piston itself.

By this invention the commencement of the suction of the .air on thecompletion of the stroke of the hammer piston is eilected by an exhaustval'vein the hammer cylinder which opens as soon as the stroke of thehammer piston is completed. Consequently the compressedair escapes fromthe hammer and pump cylinders so that atmospheric pressure isre-established and no additional aspiration is necessary. 1

Further on the commencement oi the suction of the air during the returnmovement of the hammer piston, the connecting passage between the pumpcylinder and the hammer cylinder is connected with the ham mer cylinderat a distance from the rear end of the latter which is smaller than thelength of the hammer piston. Consequently the suction action on thehammer piston is automatically interrupted as soon as the latter,towards the end of its return movement, has passed the mouth of theconnecting passage. The hammer cylinder must of course be male shortenough to enable the mouth of the connecting passage to be passed evenin the position of the hammer cylinder in which the full weight of thehammer piston counteracts the suction action.

When the mouth of the connecting passage is covered air is also enclosedbetween the hammer piston and the rear end of the cylinder. On thefurther return movement of the hammer piston it compresses the enclosedair until the impetus is destroyed, that is to say the hammer piston isbrought to a standstill. At this moment the air between the rear end orthe hammer cylinder and the hammer piston is compressed by anotherstroke of the pump, so that the hammer piston commences to be againdriven forward. The commencement of: the suction of the air and therebythe change of stroke of the hammer piston takes place accordingly quiteautomatically by means oi" the hammer piston independently or the airpump.

In order to carry out the stroke which itself started by the hammerpiston, the co action of the pump is, however, necessary, that is to saythe remainder of the air enclosed between the hammer cylinder and thepump cylinder must also be compressed and then again united with the airenclosed behind the hammer plunger. This commencenyent oi the suction ofthe air by means of the air pump need not take place precisely at thesame time as the change of stroke oi the hammer plunger, but it can takeplace somewhat earlier or later without the movement of the hammerpiston being thereby influenced. The object sought for, namely thedependence of the commencement of the suction of the air on the positionofthe hammer piston and the independence of this suction on the positionof the pump piston accordingly is attained at least so far as the latterappears necessary in consequence of the relative movements of the hammerand pump pistons caused by the large waste spaces,

The commencement oi. the suction of the air produced by the pump isoperated by a suction valve on the pump cylinder which i'incovered bythe pump piston when the hammer piston is near its rear dead point. thatis to say, is already enclosed behind the hammer piston. The pumpaspirates air towards the end of its suction stroke.

through this valve. Now in order that the pump can immediately commenceits compression action at the commencement of its compression stroke,the suction valve according to this invention is so placed that the pumpplunger uncovers the valve only The quantity of fresh air aspirated isso large that it replaces not only the unavoidable loss of air, but alsothe air enclosed behind the hammer plunger.

The combined action of the air compressed by the air pump with the airenclosed behind the hammer plunge-r takes place at the moment at whichthe hammer plunger has again been moved forward beyond the mouth of thepassage connecting the pump cylinder and the hammer cylinder.

In order that the combined action shall always take place not only atthis moment but also when the pressure of thetwo quantities of air isequal, according to this invention a branch pipe leads from theconnecting passage and connects, in direct proximity to the rear end ofthe cylinder, with the hammer cylinder and is closed by a valve openinginto the interior of the hammer cylinder only.

The invention will now be more particularly described in connection withthe accompanying drawings, in which one form of construction of a rockdrill hammer is illustrated as an example Figure 1 shows in longitudinalsection on the left a hammer cylinder and on the right hand a pumpcylinder.

Fig. 2 is a similar view showing. the pistons in different positions.

The'movement of the pump piston i is produced by a crank drive from anelectric motor or the like. The interior of the pump cylinder isconnected by ports Z with a chamber m which is closed by a suction valueit to the outside air. The upper end of the pump cylinder 70 connectswith a pipe socket 0 which is connected with a pipe socket p of thehammer cylinder 1 by means of a flexible pipe not shown in the drawings.

The pipe socket 72 is connected with a passage g which forks into twobranches g and e. The branch 9 passes axially through the rear end 7 ofthe cylinderand is closed by. a valve 6 which opens to the interior ofthe hammer cylinder 9* only and which in the example selected is shownas a simple flap valve.

The branch 9 can of course also connect with the side of the cylinder7", so long as the mouth lies immediately beneath the end f, as it alsofulfils its functions under these conditions. The branch 6 connects thetwo cylinders at a distance from the end 7' of the hammer cylinder whichis smaller than the length of the hammer piston c.

The hammer cylinder r has a pressure valve a which in the exampleselected is also formed as a flap valve, the aperture a of whichvalveliesat a distance from the tool 6- which corresponds to the length ofthe hammer plunger 0. At the bottom portion of the cylinder, ports 1)are provided, so that the chamber beyond the hammer plunger 0 is alwaysin communication with the external air.

In the top end position of the hammer plunger 0 (Figure 1) an aircushion is formed between it and the top end of the cylinder, whichcushion operates the change of stroke of the hammer piston. The pumpplunger 5 aspirates fresh air through the valve lb. When the pump makesa compression stroke the air enclosed behind the hammer plunger isunited with the air com= pressed by the pump through the valve b. Whenthe hammer plunger '0 has reached its bottom end position (Figure 2) thecompressed air escapes through the valve a thus immediatelyreestablishing atmospheric pressure. Of course the ordinary means forcontrolling heavy and light blows may be arranged in the handle of, thetool. It is evident that the invention may be utilized as a hamme toolfor all uses and all substances.

I claim as my invention- 1. In a rock-drill or like cutting machinehaving a hammer cylinder with piston and a single acting air pump foroperating it, means for rendering the change of the stroke of the hammerpiston independent from, the position ofthe pump piston and make itdependent from the position of thehammer piston, comprising an exhaustvalve in the hammer cylinder arranged to open imme diately after theforward stroke of the hammer piston whereby the change of stroke iseffected after the forward stroke, and a valve in the. rear cover of thehammer cylinder producing with its aid during the rearward stroke an aircushion between the hammer piston and the rear cylinder cover,initiating the change of stroke after the rearward stroke.

2. In a rock-drill or like cutting machine having a hammer cylinder withpiston and a single acting air pump for operating it, means forrendering the change of the stroke of the hammerpiston independent ofthe air pump, comprising an exhaust valve in the hammer cylindercontrolling the change of the piston stroke after the forward movement,a. cover on the hammer cylinder formmeans for rendering the change ofthe stroke of the hammer piston independent of the air pump comprisingan exhaust valve in the hammer cylinder controlling the change of itspiston stroke after the forward movement, a cover on the hammer cylinderforming with the top of its piston an air chamber towards the end of therearward piston stroke, and a. connection between the pump and hammercylinders connecting with the hammer cylinder at a distance from therear cover of the hammer cylinder which is smaller than the length orthe hammer piston.

4. In a rock-drill or like cutting machine, means for controlling thechange of the stroke of the hammer piston composed essentially of anexhaust valve in the hammer cylinder establishing atmospheric pressurewithin the said cylinder at the end of the forward stroke, and an airchamber formed by the cover of the hammer cylinder and the top of itspiston housing a compressed air cushion towards the end of the rearwardstroke of the piston which cushion then controls the change of thestroke.

5. In a rock-drill or like cutting machine, having a hammer cylinderwith piston and a single acting air pump for operating it, means forcontrolling the change of the stroke ofthe hammer piston comprising aconnection having a forked passage in the hammer cylinder, one branchconnecting at a distance from the rear end of the said cylinder smallerthan the length of the hammer plunger, the other branch connectingdirectly at the rear end of the hammer cylinder, and a valve locatedtowards the interior of the cylinder adapted to close said second branchand a suction valve in the pump cylinder actuated through the saidconnection and its forked passage.

In testimony whereof I afiix my signature in presence of two witnesses.

AUGUST BERNER.

'VVitnesses OSCAR BooK, HANS WALTER.

